Embodiments of this invention include an improved composition and method for suppressing water evaporation and heat loss.
The need to prevent evaporation of water from various bodies of water is known, and this is important in areas that, for example only, are generally hot, that receive little annual rainfall, or little seasonal rainfall, or which are subject to periodic droughts or water shortages. This is necessary to provide water for such purposes as drinking, irrigating crops or vegetable gardens, or other needs. In addition, where the body of water needs to be maintained at a certain temperature, such as for example, a pool for therapeutic purposes, there can be a significant cost associated with maintaining that particular temperature. Consequently, a number of agents have been developed to apply to various sized bodies of water to suppress either or both of water loss by evaporation and heat loss from such water bodies.
The use of long-chain, solid, aliphatic fatty alcohols, particularly of chain length C16 and C18, commonly known as, respectively, cetyl alcohol and stearyl alcohol, are known in the prior art for suppressing water evaporation. However issues with dispensing these materials present hurdles to their use in practice under actual use conditions. Attempts to overcome these hurdles have involved a number of approaches. The prior art teaches the need to combine these materials with solvents and dispersants or spreading agents to make their use practical under actual use conditions. These prior art compositions involve heating, combining and dispensing materials at high temperatures (between about 70 degrees C. to about 100 degrees C.). Compositions are delivered as dispersions, emulsions, solutions or solids.
U.S. Pat. Nos. 4,162,990 and 4,250,140 teach that the smallest chain length that can seriously be regarded as an evaporation retardant is C16. Surprisingly, the present inventors find that Laureth-2 with a carbon length of C12 performs unexpectedly well for suppressing water evaporation and heat loss.
Reiser (U.S. Pat. No. 3,528,764) discloses a method and apparatus for retarding water evaporation from water surfaces through the use of solid fatty alcohols delivered as a dispersion. Alternatively an emulsion can be formed from the dispersion by including a surfactant such as ethoxy derivatives of fatty alcohols. The inventor specifically indicates a preference to use a fatty alcohols having from 16 to 18 carbon atoms.
O'Brien (U.S. Pat. No. 6,303,133 B1) discloses a composition that forms a monolayer to suppress water evaporation, comprising an aliphatic alcohol component having from C12-C24 and powdered calcium hydroxide. Cetyl alcohol and octadecanol can be used; cetyl alcohol (hexadecanol) having a chain length of C16 is preferred.
Rowlette (U.S. Pat. No. 4,162,990) discloses using a polyethylene glycol that is soluble in both water and the fatty alcohol (such as docosanol, docosanoic acid or octadecanol) as a spreading agent for the fatty alcohol on the surface of a body of water. The particles are mixed with particles of a filler material capable of generating a gas upon contact with water.
In U.S. Pat. No. 4,250,140 Rowlette discloses using a polyethylene glycol, such as those in the CARBOWAX® series (Registered trademark of Union Carbide Chemicals & Plastics Technology Corp., Danbury, Conn.), as a spreading agent for a film-forming agent. This patent states that C16 is the smallest chain length that can seriously be regarded as an effective evaporation retardant.
U.S. Pat. No. 3,531,239 indicates that various fatty alcohols, such as octadecanol, hexadecanol, nonadecanol, and pentadecanol could be used as evaporation retardants for water although the inventor states that a chain length from C16 to C18 are generally preferred.
Egan (U.S. Pat. No. 3,415,614) discloses the addition of a heterocyclic, 5-membered ring compound, one of which is oxygen, to at least one solid aliphatic alcohol ranging from C12-C20, to form a solid, self-dispersing composition. The aliphatic alcohols include myristyl, cetyl and stearyl alcohols and mixtures thereof. The most preferred composition comprises cetyl and stearyl alcohols which retards evaporation by about 30-40%.
In U.S. Pat. No. 3,391,987 Myers discloses compositions using water-soluble saccharides as carriers for the fatty alcohols where hexadecanol and octadecanol with chain lengths C16 and C18 are especially preferred. Unsaturated alcohols such as oleyl alcohol may be used, but are not preferred.
Cox (U.S. Pat. No. 3,257,162) discloses glycol esters, glycol amides and ethoxylated amides and ethoxylated derivatives thereof that are effective in retarding evaporation of aqueous solutions of normally volatile organic substances.
In U.S. Pat. No. 3,959,154 Cox discloses agents to retard the evaporation of ammonia and amines from essentially aqueous solutions by adding thereto an alkyl ether having the formula:R—(O[CH2]y)n—R′where
R is an alkyl group containing from 8 to 30 carbon atoms, and
R′ is an —OH or —NH2 group,
y is an integer of 2 to 4; and
n is an integer of 1 to 10.
The inventor notes that the utility of these compositions is predicated on the fact that they effect the evaporation of dissolved ammonia or amines to a far larger extent than their effect on the evaporation of water.
In U.S. Pat. No. 2,903,338 Dressler discloses the use of finely divided and wetted/suspended fatty acid alcohols, preferably C16 to C18, dispersed in water or emulsified with sodium lauryl sulfate or sodium dodecylbenzene sulfonate to form a film that leads to a reduction in water loss by evaporation.
Malkemus (U.S. Pat. No. 3,036,880) discloses the use of ethylene glycol and propylene glycol monoesters of long chain fatty acids to form films on the surface of water. The patentee notes that the fatty acid must have at least 14 carbon atoms since esters from the lower acids do not appear to offer any advantages. Benzene is the preferred solvent.
In U.S. Pat. No. 3,146,059 Suzuki et al. disclose the use of derivatives of aliphatic alcohols with carbon chain lengths of 22 to 16 or docosanol to cetanol in compositions for retarding water evaporation. The claims are addressed to longer chain structures, having the general formula:CH3—(CH2)m-O—(CH2—CH2—O)n-Hwhere m is 15-21; and
n is 1-5,
which may be mixed with a compound such as urea, salts of carboxymethylcellulose or alginic acid. Fatty alcohol derivatives of this invention with 1 mole of ethylene oxide showed an average reduction in the evaporation rate of water of 56%, 22%, 6% respectively for C22, C18, C16. Furthermore, evaporation rate reduction decreased from an average of 56% for 1 mole of ethylene oxide to about 9% for 5 moles of ethylene oxide. Taken together these results clearly indicate that the expected effect on the evaporation rate of water for ethoxylates of fatty alcohols with a carbon chain length less than C16 would be close to zero! Thus it would be very surprising and unexpected that a fatty alcohol ethoxylate with a carbon chain length of C12 and 2 moles of ethylene oxide, such as Laureth-2 would have any effect on the evaporation rate of water.
Mazur (U.S. Pat. No. 3,241,908) discloses a method for preparing a monomolecular film former for controlling evaporation from water surfaces, using fatty acid alcohols such as n-hexadecanol and n-octadecanol, which show a 25-35% reduction in the evaporation rate of water.
In U.S. Pat. No. 3,437,421 Harwood discloses the use of long chain aliphatic alcohols as agents for retarding water evaporation and a method by which solid long-chained alcohols are liquefied by heating and then sprayed onto the surface of a body of water. The preferred compounds were the C16 and C18 compounds hexadecanol and octadecanol; unsaturated alcohols, such as oleyl alcohol, had a lower efficiency than the saturated alcohols.
In U.S. Pat. No. 3,650,980 Gothel et al. disclose a film forming composition to retard evaporation loss that comprises a higher alkyl alcohol and up to three weight percent of an ortho-silicic acid ester of an ethoxylated alcohol. Ethoxylated lauryl- as well as stearyl-alcohols are stated to be of restricted applicability as non-ionic surfactants.
Hall (U.S. Pat. No. 4,172,058) discloses the use of a mixture of hexadecanol and octadecanol, both as a mixture of liquids, or a dry mixture thereof, as a composition to retard evaporation of fluid from an aqueous mixture containing “H-SPAN”, a hydrolyzed starch-polyacrylonitrile graft copolymer.
In U.S. Pat. No. 4,707,359 McMullen discloses the use of fatty acid alcohols in conjunction with an insecticide to form a layer on a water surface and kill insects, such as mosquitoes. The particular compounds are described in Great Britain Pat. No. 1,557,804A, with the composition including an oleyl poly-ethoxy, poly-propoxy mixed ether. The composition may include a solvent, such as water, kerosene, hexane deiselene, heptane and gas oil.
Koester et al. (U.S. Pat. No. 4,932,994) disclose a paraffin-containing aqueous dispersion or a self-emulsifying solution in an organic solvent, to form films on the surface of water.
In contrast to the prior art compositions, embodiments of the present invention utilize polyoxyethylene alkyl ethers with carbon chain lengths less than C16 as the active agent. For example, polyoxyethylene (2) lauryl ether is a polyoxyethylene lauryl ether having a carbon chain length of C12 with 2 moles of ethylene oxide which performs unexpectedly well for suppressing water evaporation and heat loss. Furthermore, because it is a liquid at ambient conditions and is self-dispersing, it can be used as is, without the need for any further processing, without the need for any added solvents, carriers, dispersants or spreading agents, and without the need for any specialized equipment for application.
The fatty alcohol ethoxylate can be delivered in one of several forms: a neat liquid, a solution, or a dispersion in an appropriate solvent or carrier, without the need of any additional dispersant or spreading agent.
The range for delivery of the fatty alcohol ethoxylate in dilution is from about 0.1% to about 90% by weight in one embodiment of the invention. In another embodiment, the range for delivery of the fatty alcohol ethoxylate is from about 0.5% to about 50% by weight, and in another embodiment, the range for delivery of the fatty alcohol ethoxylate is from about 1% to about 20% by weight.
In one embodiment, the fatty alcohol ethoxylate is delivered as a suspension in water, thereby avoiding the use of hazardous or flammable solvents.
Additional embodiments may use a thickening agent of sufficient yield to stabilize the dispersion until use. Other ingredients such as preservatives, colorants and fragrance can be added to the composition as desired.